Pons Racing's Yu Kanamaru led the way on the first day of testing for the rebranded Formula 3.5 V8 series at Jerez.

The Japanese racer contested the final three rounds of the 2015 series - which marked the end of Renault's involvement - and led the opening day under RPM Racing's management. Kanamaru set his time of 1m28.067s in the morning, and felt there was more time in the car, after spinning later in the day.

"In the morning I had great driveability and the laptime came in pretty easily," he said. "We even had enough potential to improve again, but I hit too much of a curb and spun. In the afternoon, we made changes that caused some understeer, and with the new tires we did not perform at our best. I think we will revert to the previous settings for tomorrow."

A double race winner in 2015, Egor Orudzhev was quickest in the afternoon for Arden, and just 0.016 seconds shy of Kanamaru's morning best.

Championship runner-up Matthieu Vaxiviere transferred from regular team Lotus to assist the development of newcomer Spirit of Racing.

"We worked a lot to prepare for next season," said Vaxiviere, who finished in the top three in both sessions. "The team is very professional, they work a lot and it is an interesting experience for me. It wasn't easy to put in a good lap with the red flags. The car is fast, we must continue to look at everything in detail."

Spirit of Race is one of three new teams to sign-up for next season, and 10 teams in total have confirmed their participation. Fellow newcomers RP Motorsports and Teo Martin Motorsport didn't appear at Jerez.

FR2.0 star Jake Hughes tested for Strakka Racing and frontrunner Matevos Isaakyan partnered Kanamaru at Pons Racing. Aitken was second fastest in the morning, half-a-second off of Kanamaru, but believed his fourth position in the afternoon was unrepresentative.

"The morning went very well because I was the quickest among the rookies," said Aitken. "I am satisfied with our progression, even though I couldn't show what I can do in the afternoon with all these red flags."

The red flag was shown twice in the opening session following the off-track excursions by GP3 regular Marvin Kirchhofer and Comtec's Jehan Daruvala.

Hughes underlined his ability by offering the closest challenge to Orudzhev in the afternoon. The test concludes on Wednesday.